Preliminary Investigation On The Taxonomy And Ecology Of Benthic Ciliates In Intertidal Area

The intertidal zone is the area that is exposed to the air at low tide and submerged at high tide. The natural environment of intertidal zone changes extremely every day because of natural condition alternations and human activities. Therefore, organisms in the intertidal zone are more resistant to a bad condition and adapted to an environment of harsh extremes. In contrast to pelagic ecosystem, there are much higher species richness and habitat diversification in benthic ecosystem. However, our knowledge about the community structure and function of benthic ciliates is rather limited. In China the study of marine ciliate taxonomy was mostly focused on water mass organisms and the marine benthic forms are largely not known, and even no research has been carried out to investigate the community strucutre and distribution of marine benthic ciliates.From July 29, 2007 to July 2, 2008, we conducted a one-year sediment sampling at two stations in the intertidal area of Qingdao Bay, China. Station S-QH (composed of sand 55.7%, silt 36.6%, clay 7.7%) is closed to the high tide mark, and statoin S-QL (composed of sand 96.9%, silt 2.4%, clay 0.8%) is closed to the low tide mark. Each triplicate of 0-8cm core samples was sliced to 0-0.5cm, 0.5-2cm, 2-4cm & 4-8cm layers, and preserved with ice-cold glutaraldehyde in 2% final concentration. Water temperature and salinity were measured in situ, chlorophyll a, phaeophytin a and organic matter content were determined in laboratory. Protargol staining method and the quantitative protargol stain (QPS) were applied to identify and enumerate benthic ciliates. More than ten species were recorded for the first time in China. Among these, Metopus contortus and Paramecium calkinsi were described in detail. A new species, viz. Tunicothrix multinucleata n. sp. was discovered and comparatively studied with its congener T. wilberti.The annual average ciliate abundance was 7922 inds./10cm2 (99 inds./ml) at station S-QL, and 11993 inds./10cm2 (300 inds./ml) at station S-QH. The highest abundance recorded up to now was found in the top 0-0.5cm layer at Station S-QH in July 2007 and attained 6016 inds./ml. Ciliates of 0-0.5cm layer contributed to an average of 35% of total ciliate abundance in station S-QL and up to 75% in station S-QH. Station S-QL had a higher species richness/species diversity than station S-QH, following the seasonal sequence as spring > autunm for station S-QL, winter > spring > summer > autumn for station S-QH. Correlation analysis showed that the ciliate abundance was significantly positively correlated with temperature (p < 0.01), phaeophytin a and organic matter content (p < 0.05), and significantly negatively correlated with salinity (p < 0.01).